Mistaken Identity — Piezo Actuators Not Test Pads

June 18, 2021 by Chris Lott 16 Comments

One hard disk recently failed in the EEVBlog laboratory’s NAS. Keeping true to his catch phrase, [Dave “Tear it Apart” Jones] opened it up and gave us an inside tour of a modern hard disk drive. There are so many technological wonders to behold in modern HDDs these days — the mechanical design, electronics and magnetics, and the signal processing itself which is basically an advanced RF receiver — that we can forgive [Dave] for glossing over a system of piezo actuators thinking they were manufacturing test points. Even knowing they are actuators, you have to stare at them and think for a bit before your brain accepts it.

Later realizing the mistake, he made a follow-up video (down below) focusing on just the disk head actuator arms and this micro-actuation system (or perhaps they are milli-actuators). The basic concept is a pair of piezoelectric transducers mounted on either side of the short arm holding the read head. Presumably they are driven out of phase to flex the arm left or right, but the motion is imperceptible to the eye — even under magnification, [Dave] was not able to discern any motion when he pulsed the transducers. When you consider that these micro-actuators are mounted on the main actuator arm, which itself is also in motion, the nested control loop arrangement to maintain nanometers of accuracy is truly amazing. Check out this 45 second explanatory video by Western Digital which has a good animation of the concept.

If you want to see your HDD in operation without taking it apart, check out the transparent drive we wrote about last month. And to read more about esoteric actuators, check out this article from 2015 which contains one of the longest words to appear in our pages — magnetorheological. If you’ve experience a hard disk failure, which thankfully is becoming rarer these days, do you chunk it or tear it apart?

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Cloned Memory Module Fixes Broken Scopemeter

June 17, 2021 by Dan Maloney 9 Comments

Finding broken test gear and fixing it up to work again is a time-honored tradition among hackers. If you’re lucky, that eBay buy will end up being DOA because of a popped fuse or a few bad capacitors, and a little work with snips and a soldering iron will earn you a nice piece of test gear and bragging rights to boot.

Some repairs, though, are in a class by themselves, like this memory module transplant for a digital scopemeter. The story began some time ago when [FeedbackLoop] picked up a small lot of broken Fluke 199C scopemeters from eBay. They were listed as “parts only”, which is never a good sign, and indeed the meters were in various states of disassembly and incompleteness.

The subject of the video below was missing several important bits, like a battery and a power connector, but most critically, its memory module. Luckily, the other meter had a good module, making reverse engineering possible. That effort started with liberating the two RAM chips and two flash chips, all of which were in BGA packages, from the PCB. From there each chip went into a memory programmer to read its image, which was then written to new chips. The chip-free board was duplicated — a non-trivial task for a six-layer PCB — and new ones ordered. After soldering on the programmed chips and a few passives, the module was plugged in, making the meter as good as new.

While we love them all, it’s clear that there are many camps of test gear collectors. You’ve got your Fluke fans, your H-P aficionados, the deep-pocketed Keithley crowd — but everyone loves Tektronix.

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Digital X-Ray Scanner Teardown Yields Bounty Of Engineering Goodies

June 14, 2021 by Dan Maloney 12 Comments

We’ll just go ahead and say it right up front: we love teardowns. Ripping into old gear and seeing how engineers solved problems — or didn’t — is endlessly fascinating, even for everyday devices like printers and radios. But where teardowns really get interesting is when the target is something so odd and so specialized that you wouldn’t normally expect to get a peek at the outside, let alone tramp through its guts.

[Mads Barnkob] happened upon one such item, a Fujifilm FCR XG-1 digital radiography scanner. The once expensive and still very heavy piece of medical equipment was sort of a “digital film system” that a practitioner could use to replace the old-fashioned silver-based films used in radiography, without going all-in on a completely new digital X-ray suite. It’s a complex piece of equipment, the engineering of which yields a lot of extremely interesting details.

The video below is the third part of [Mads]’ series, where he zeroes in on the object of his desire: the machine’s photomultiplier tube. The stuff that surrounds the tube, though, is the real star, at least to us; that bent acrylic light pipe alone is worth the price of admission. Previous videos focused on the laser scanner unit inside the machine, as well as the mechatronics needed to transport the imaging plates and scan them. The video below also shows experiments with the PM tube, which when coupled with a block of scintillating plastic worked as a great radiation detector.

We’ve covered a bit about the making of X-rays before, and a few of the sensors used to detect them too. We’ve also featured a few interesting X-ray looks inside of tech, from a Starlink dish to knock-off adapters.

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Aircraft Compass Teardown

May 30, 2021 by Al Williams 6 Comments

We didn’t know what a C-2400 LP was before we saw [David’s] video below, but it turned out to be pretty interesting. The device is an aircraft compass and after replacing it, he decided to take it apart for us. Turns out, that like a nautical compass, these devices need adjustment for all the metal around them. But while a ship’s compass has huge steel balls for that purpose, the tiny and lightweight aviation compass has to be a bit more parsimonious.

The little device that stands in for a binnacle’s compensators — often called Kelvin’s balls — is almost like a mechanical watch. Tiny gears and ratchets, all in brass. Apparently, the device is pretty reliable since the date on this one is 1966.

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Teardown: RADICA I-Racer

May 26, 2021 by Tom Nardi 3 Comments

Long before the Oculus Rift and HTC Vive came along, some of the biggest names in gaming tried to develop practical stereoscopic displays. These early attempts at virtual reality (VR) were hindered by the technical limitations of their time, and most never progressed beyond the prototype stage. Of the ones that did make it to retail shelves, none managed to stick around for very long. The best known example is Nintendo’s Virtual Boy, which ended up being a financial disaster upon its release in 1995 and some regard as the gaming giant’s greatest blunder.

Despite these public failures, Radica still felt compelled to throw their hat into the ring. Best known for their line of relatively simplistic LCD handheld games, the company produced several rudimentary stereoscopic stand-alone titles in the late 1990s to try and cash in on the VR fad. Among the later entries in this series was 1999’s NASCAR i-Racer, which at least externally, looks quite a bit like modern VR headset.

Featuring a head-mounted stereoscopic display, a handheld controller, force feedback, and integrated headphones, you’d certainly be forgiven for thinking the i-Racer was ahead of its time. But its reliance on the primitive LCD technology that put Radica on the map, combined with the need to keep the game as cheap as possible, keeps the experience planted firmly in the 1990s. But perhaps there’s something we can do about that.

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Inside The VIC-20

May 19, 2021 by Al Williams 51 Comments

Commodore machines are well-loved around here, but usually when you think Commodore, you think about the Commodore 64, or maybe the PET or Amiga. But the Commodore 64 had an older sister, the VIC 20. This was the first computer to sell a million units and has a lot in common with its better-known successor. The machine was only made for a few years, and [Dubious Engineering] has been restoring one over a few videos. In the video below, he opens it up for a look inside, among other things.

If you want to get straight to the opening, you’ll need to fast forward about 5 and a half minutes. The keyboard pulls off and a nice old-fashioned set of cables made from individual wires connect to the skinny main board with all the smarts on it. No ribbon cables or flex PCBs!

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A “Disgusting” 1980s Computer Restored

May 17, 2021 by Al Williams 42 Comments

It takes a special eye to see a junkyard car and envision it as your latest hotrod. The guys at RMC found what they termed a “disgusting” Acorn Electron and decided to restore it to its former glory. The Electron was a budget version of the BBC micro with a 6502 running at 2 MHz when executing code from ROM and 1 MHz when it hit the RAM. Apparently, at least some of the bus was operating at 4 bits instead of 8. Go figure.

The 1982 machine was meant to head off the Sinclair ZX and was set to sell for about £200. However, the machine didn’t catch on like the Sinclair and undersold it by around 20 times with a paltry quarter of a million units.

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